Suction pick-up apparatus for electrical or electronic components

ABSTRACT

A pick-up head (10) of the apparatus has three alternative pick-up surfaces (24,34,64) formed respectively on a body (16), a first piston member (30), and a second piston member (60). The first piston member (30) is slidable in a cylinder (22a) formed in the body (16) and the second piston member (60) is slidable in a cylinder (48a) formed in the first piston member (30). The piston members (30,60) are movable between projecting positions and retracted positions. When both piston members are retracted, the surface (24) of the body (16) is used, when only the second piston member (60) is retracted, the surface (34) of the first piston member (30) is used, and, when neither piston member is retracted, the surface (64) of the second piston member (60) is used.

This is a continuation of co-pending application Ser. No. 207,362 filedon June 15, 1988, now U.S. Pat. No. 4,852,247.

BACKGROUND OF THE INVENTION

This invention is concerned with suction pick-up apparatus forelectrical or electronic components. Such apparatus is used in componentplacement machines for placing components of varying sizes on a suitablesubstrate, for example a printed circuit board. Such apparatus comprisesone or more pick-up heads movable between a location at which theypick-up a component by suction and a location at which they release thecomponent on to the substrate. Such pick-up heads have pick-up surfacesagainst which the component is held and for accurate placement it isessential that the size of the pick-up surface at least approximatelycorresponds to the size of the component. If the pick-up surface is toosmall the placement force cannot be uniformly applied thereto by thehead and the component may tip. If, on the other hand, the pick-upsurface is too large, the component cannot be readily centred on thesurface and the size of the pick-up surface may restrict access to partsof the substrate because of the possibility of fouling already placedcomponents.

In order to match the pick-up surface to the component, pick-up headshave been constructed with replaceable tips. A magazine of tips withpick-up surfaces of different sizes is provided and, when a component ofa different size is to be placed, the pick-up head is moved to themagazine and a tip exchange takes place. This reduces the productivityof the machine. It is also possible to utilise a plurality ofalternative pick-up heads each with a different size of pick-up surfacebut this would be expensive and complex.

The specification of GB Patent Application No. 8702618 describes asuction pick-up apparatus in which pairs of alternative pick-up headsare mounted on carriers spaced around a carousel. The carousel turns tobring the carriers to component pick-up and placement locations and thecarriers can be moved relative to the carousel to bring either of thealternative pick-up heads into operation. The pick-up heads on eachcarrier each have two alternative pick-up surfaces. A first pick-upsurface is formed on a body of the pick-up head and a second pick-upsurface is formed on a piston member which can project beyond the bodyor can be retracted into a cylinder within the body. The piston memberis retracted when vacuum is applied to the cylinder and projects whenair under pressure is applied thereto. It has been found thatsubstantially all the components it is desired to place can be placedusing one or other of the pick-up surfaces of one pick-up or other ofthe pick-up heads.

It is an object of the present invention to provide a pick-up head whichcan pick-up and place substantially all the components required to beplaced in a placement machine without requiring tip exchanges.

BRIEF SUMMARY OF THE INVENTION

The invention provides suction pick-up apparatus for electrical orelectronic components, comprising a pick-up head comprising a bodyhaving a first pick-up surface at one end portion thereof, a firstcylinder within the body, a first piston member mounted for slidingmovement in the first cylinder and terminating with a tip having asecond pick-up surface of smaller area than the first pick-up surface,the first piston member being slidable between a projecting positionthereof in which its tip projects through an opening in the firstpick-up surface beyond the first pick-up surface and a retractedposition thereof in which the tip of the first piston member does notproject beyond the first pick-up surface, a first port extending throughthe body through which air can be admitted to the first cylinder todrive the first piston member into its projecting position or throughwhich vacuum can be applied to retract the first piston member into itsretracted position, a second cylinder within the first piston member, asecond piston member mounted for sliding movement in the second cylinderand terminating with a tip having a third pick-up surface of smallerarea than the second pick-up surface, the second piston member beingslidable between a projecting position thereof in which its tip projectsthrough an opening in the second pick-up surface beyond both the firstand the second pick-up surfaces and a retracted position thereof inwhich the tip of the second piston member does not project beyond thesecond pick-up surface, a second port extending through the first pistonmember through which air can be admitted to the second cylinder to drivethe second piston member into its projecting position or through whichvacuum can be applied to retract the second piston member into itsretracted position, and a vacuum port through which component-retainingvacuum can be applied to an opening in the third pick-up surface whenthe first and the second piston members are in their projectingpositions, to the opening in the second pick-up surface when the firstpiston member is in its projecting position and the second piston memberis in its retracted position, and to the opening in the first pick-upsurface when the first piston member is in its retracted position.

In a suction pick-up apparatus according to the last precedingparagraph, it is found that with suitable design of the sizes of thepick-up surfaces, substantially all the components desired can bepicked-up and placed by the pick-up head without requiring tip exchangesor the provision of alternative pick-up heads.

Preferably, said vacuum port extends through the body and communicates,when the first piston member is in its retracted position with a firstannular passage between the body and the first piston member whichcommunicates with the opening in the first pick-up surface, said vacuumport communicating, when the first piston member is in its projectingposition with a second annular passage between the body and the firstpiston member which communicates, when the second piston member is inits retracted position, with the opening in the second pick-up surfaceand, when the second piston member is in its projecting position, withthe opening in the third pick-up surface. This arrangement allows theuse of a single vacuum port.

Preferably, said first piston member is retained within said firstcylinder by a transversely-extending member fixed to the first pistonmember and entering a longitudinally-extending slot in said body. Thisarrangement simplifies the construction. Conveniently, the saidtransversely-extending member is in the form of a pipe forming saidsecond port.

Conveniently, said second piston member is retained within said secondcylinder by a sliding connection with said first piston member. Saidsliding connection may comprise a shaft fixed to said first pistonmember and projecting into a passage in said second piston member, ahead formed on said shaft within said passage, and abutment meansmounted on said second piston member and arranged to project into saidpassage to retain said head in said passage.

It is found that a suction apparatus according to the invention canpick-up and place substantially all required components if the firstpick-up surface is circular and has a diameter of between 1.5 and 2millimeters, the second pick-up surface is circular and has a diameterof between 5.5. and 6.5 millimeters, and the third pick-up surface iscircular and has a diameter of between 12.5 and 13.5 millimeters.

BRIEF DESCRIPTION OF THE DRAWINGS

There now follows a detailed description, to be read with reference tothe accompanying drawings, of a suction pick-up apparatus for electricalor electronic components which is illustrative of the invention. It isto be understood that the illustrative apparatus has been selected fordescription by way of example and not of limitation of the invention.

In the drawings:

FIG. 1 is an enlarged side elevational view, partly in section, of apick-up head of the illustrative apparatus, showing the pick-up head incondition for picking-up and placing large components;

FIG. 2 is a similar view to FIG. 1 but showing the pick-up head incondition for picking-up and placing medium-sized components; and

FIG. 3 is a similar view to FIGS. 1 and 2 but showing the pick-up headin condition for picking-up and placing small components.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENT OF THE INVENTION

The illustrative pick-up apparatus is for electrical or electroniccomponents and comprises a pick-up head 10, a plunger 12 on which thehead 10 is fixedly-mounted by a clamping screw 14, means (not shown) formoving the plunger 12 and hence the head 10 up or down to pick-up orplace a component (said moving means being of conventional constructione.g. a piston and cylinder assembly); and means (not shown) for movingthe plunger 12 and hence the head 14 between a pick-up position at whichthe head 10 can pick-up a component and a placement position above asubstrate on to which the component is to be placed (said means being ofconventional construction, e.g. a carousel on which the plunger ismounted).

The pick-up head 10 comprises a body 16 which is generally cylindricalbut with an external flange 18 at an upper end portion thereof. Theclamping screw 14 is threadedly-received in a threaded bore 20 in saidflange 18. A cylindrical passage 22 passes vertically through the body16 and is entered by the bore 20. A lower portion of the plunger 12 isreceived in an upper portion of the passage 22 and is (asaforementioned) clamped by the clamping screw 20. The body 16 has afirst pick-up surface 24 of the head 10 formed at one end portionthereof, the surface 24 being formed by a resilient washer 26 mounted ona downward annular projection 28 of the body 16, the projection 28 beingconcentric with the passage 22. The washer 26 has a circular opening 29therethrough.

The portion of the passage 22 below the plunger 12 forms a firstcylinder 22a of the head 10 within the body 16. A first piston member 30of the head 10 is mounted for sliding movement, up and down, in thefirst cylinder 22a and terminates at its lower end with a tip having asecond pick-up surface 34 of smaller area than the first pick-up surface24. The second pick-up surface is formed by a resilient washer 36mounted on a downward annular projection 38 of the first piston member30, the projection 38 being concentric with the projection 28 of thebody 16 and with the passage 22. The washer 36 has a circular opening 37therethrough. The first piston member 30 is slidable between aprojecting position thereof (shown in FIG. 2) in which its tip projectsthrough the opening 29 in the washer 28 beyond the first pick-up surface24, and a retracted position of the first piston member 30 (shown inFIG. 1) in which the tip does not project beyond the first pick-upsurface 24.

The first piston member 30 is generally cylindrical and is a snug fit inthe passage 22. The lowermost portion 30a of the member 30 is of reduceddiameter so that an annular passage 40 is formed between the body 16 andthe member 30. The portion 30b of the member 30 immediately above theportion 30a is a snug fit in the passage 22 so that the upper end of thepassage 40 is substantially sealed. The portion 30c of the member 30immediately above the portion 30b is of reduced diameter so that anannular passage 42 is formed between the body 16 and the member 30, thepassage 42 being substantially sealed at its upper and lower ends byportions of the member 30 which are a snug fit in the passage 22. Atransverse passage 44 extends radially through the portion 30c andcommunicates at both ends with the passage 42. The first piston member30 also has a cylindrical passage 48 passing longitudinallytherethrough, the passage 48 being concentric with the passage 22. Anupper portion 50 of the passage 48 is of increased diameter and isthreaded. A plug 52 is threadedly received in the portion 50 and sealsthe upper end of the passage 48.

A first port 54 extends through the body 16 into the passage 48 abovethe first piston member 30. The port 54 comprises a radial threaded bore56 in the body 16 into which a pipe connection 58 is screwed. Throughthe first port 54, air can be admitted to the first cylinder 22a todrive the first piston member 30 into its projecting position or vacuumcan be applied to suck the first piston member 30 into its retractedposition.

The portion of the passage 48 below the plug 52 forms a second cylinder48a of the head 10 within the first piston member 30. A second pistonmember 60 is mounted for sliding movement up and down in the secondcylinder 48a and terminates at its lower end with an annular tip havinga third pick-up surface 64 of smaller area than the second pick-upsurface 34. The second piston member 60 is slidable, up and down, in thesecond cylinder 48a between a projecting position thereof (shown in FIG.3) in which its tip projects through the opening 37 in the secondpick-up surface 34 beyond both the first and the second pick-up surfaces24 and 34, and a retracted position thereof (shown in FIGS. 1 and 2) inwhich the tip of the second piston member 60 does not project beyond thesecond pick-up surface 34.

The second piston member 60 has a lowermost portion 60a of reduceddiameter. The portion 60a terminates with the tip of the piston member60. An annular passage 66 is formed between the portion 60a and thefirst piston member 30. Immediately above the portion 60a thereof, thepiston member 60 has a portion 60b which is a snug fit in the passage 48and substantially seals the upper end of the passage 66. Immediatelyabove the portion 60b thereof, the piston member 60 has a portion 60c ofreduced diameter so that an annular passage 68 is formed by the portionof the passage 48 between the portion 60c and the first piston member30. A transverse passage 70 extends radially through the portion 60c andcommunicates at both ends with the passage 68. Immediately above theportion 60c thereof, the piston member 60 has a portion 60d which is asnug fit in the passage 48 and substantially seals the upper end of thepassage 68. Immediately above the portion 60d thereof, the piston member60 has an upper portion 60e of reduced diameter. A longitudinal passage72 extends upwardly in the second piston member 60 from an opening 73 inthe third pick-up surface 64. The passage 72 extends upwardly therein,and communicates with the transverse passage 70. A further longitudinalpassage 74 enters the second piston member 60 through the upper surfaceof the upper portion 60e thereof and extends downwardly through theportion 60d into the portion 60c but without communicating with thepassages 70 and 72. A shaft 76 mounted on the plug 52 extends downwardlyinto the passage 74 and has an enlarged head 78 within the passage 74which is a sliding fit in the passage 74. A transverse pin 80 set in theportion 60e extends across the passage 74 so that the head 78 cannotleave the passage 74. The pin 80, thus, forms abutment means mounted onthe second piston member 60 and arranged to project into the passage 74to retain the head 78 in the passage 74.

The head 10 also comprises a second port 84, extending through the firstpiston member 30, through which air can be admitted to the secondcylinder 48a to drive the second piston member 60 into its projectingposition or through which vacuum can be applied to suck the secondpiston member into its retracted position. The second port 84 comprisesa transverse threaded bore 86 in the first piston member 30, and a metalpipe 88 threadedly-received in the bore 86 and extending through alongitudinal slot 90 in the body 16.

The head 10 also comprises a vacuum port 94 through whichcomponent-retaining vacuum can be applied to the opening 73 of thepassage 72 in the third pick-up surface 64 when the first and the secondpiston members 30 and 60 are in their projecting positions (FIG. 3), tothe opening 37 in the second pick-up surface 34 when the first pistonmember 30 is in its projecting position and the second piston member 60is in its retracted position (FIG. 2), and to the opening 29 in thefirst pick-up surface 24 when the first piston member 30 is in itsretracted position (FIG. 1).

The vacuum port 94 comprises a radial threaded bore 96 in the body 16and a pipe connection 98 threadedly-received in the bore 96. The port94, thus, extends through the body 16. The bore 96 enters the passage 22below the portion 30b and communicates, when the first piston member 30is in its retracted position (FIG. 1) with the annular passage 40 whichcommunicates with the opening 29 in the first pick-up surface 24. Whenthe first piston member 30 is in its projecting position (FIGS. 2 and3), the vacuum port 94 enters the passage 22 above the portion 30b andcommunicates instead with the annular passage 42. When the second pistonmember 60 is in its retracted position (FIG. 2), the annular passage 42communicates via the transverse passage 44 with the annular passage 66which in turn communicates with the opening 37 in the second pick-upsurface 34. When the second piston member 60 is in its projectingposition (FIG. 3), the annular passage communicates, via the transversepassage 44, the annular passage 68, and the transverse passage 70, withthe passage 72 which communicates with the opening 73 in the thirdpick-up surface 64.

The first piston member 30 is retained within the first cylinder 22a bythe pipe 88 which forms a transversely-extending member fixed to thefirst piston member 30 and entering the longitudinally extending slot 90in the body 16. The slot 90, thus, limits the movement of the firstpiston member 30 relative to the body 16 and thereby determines theretracted and projecting positions of the member 30. The second pistonmember 60 is retained within said second cylinder 48a by the slidingconnection with the fist piston member 30 formed by the head 78 of theshaft 76 sliding in the passage 74. Engagement of the head 78 withbottom of the passage 74 and with the pin 80 limits the movement of thesecond piston member 60 relative to the first piston member 30 andthereby determines the retracted and projecting positions of the member60.

In the operation of the illustrative pick-up apparatus, when it isdesired to pick-up and place a large component, vacuum is applied to allthree ports 54, 84 and 94. This sucks the first and second pistonmembers 30 and 60 into their retracted positions (as shown in FIG. 1).The component can now be picked up on the first pick-up surface 24, byvacuum applied to the opening 29, and placed with a short blast of airapplied to the port 94 ensuring release from the surface 24. When it isdesired to pick-up and place a medium sized component, vacuum is appliedto the ports 84 and 94 while air under pressure is applied to the port54. This blows the first piston member 30 into its projecting position(FIG. 2) with the second piston member 60 moving with the first pistonmember but remaining in its retracted position relative to the firstpiston member 30. During this movement, the pipe 88 moves from the topto the bottom of the slot 90. The second pick-up surface 34 is now proudof the first pick-up surface 24 and the component can now be picked upon the surface 34 by the vacuum which is now being applied to theopening 37. When it is desired to pick-up and place a small component,vacuum is applied to the port 94 while air under pressure is applied tothe ports 54 and 84. This blows both the first piston member 30 and thesecond piston member 60 into their projecting positions (FIG. 3). Thethird pick-up surface 64 is now proud of both the surfaces 24 and 34 andthe component can be picked up by the vacuum which is now being appliedto the opening 73.

I claim:
 1. A pick-up head for picking up electronic componentscomprisinga body having an annular pick-up surface at the bottom thereofdefining a first suction area and a vertical blind bore extendingupwardly from said first suction area, a first piston member slidablydisplacable within said bore between selected upper and lower positionsand havingtop portion for sealing said bore, a second annular pick-upsurface at the bottom thereof defining a second smaller suction area anda vertical blind bore extending upwardly from said second area, a secondpiston member slidably displaceable within said first piston borebetween selected upper and lower positions, and havinga top portion forsealing said bore, a third annular pick-up surface at the bottom thereofdefining a third yet smaller suction area and a vertical blind boreextending upwardly from said third area, conduit means extending throughsaid body communicating with said body bore above said first pistonmember and means for connecting a pressure or vacuum source to saidsecond piston member includingan enlarged opening in said body, pipemeans passing through said enlarged opening and through said firstpiston member below the top portion thereof and above said second pistonmember, said enlarged area having a size selected so that said firstpiston member carrying said pipe means can be displaced between saidfirst piston member upper and lower positions.
 2. A pick-up headaccording to claim 1 wherein said enlarged opening means comprises stopmeans for limiting the upward and downward movement of said first pistonelement.
 3. A pick-up head according to claim 2 further comprising stopmeans for limiting the upward and downward movement of said secondpiston element relative to said first piston element.